The Demon's Assistant
by bipyramid
Summary: Bill finds another way to get what he wants.
1. Prologue

Stanford Pines wasn't going to ruin everything.

Bill had worked to secure this universe for himself long ago, even before the arrival of its citizens. He had woven himself into the threads of history, hiding in every culture. He was the giver of knowledge, the bringer of light and the muse of artists and inventors. Humans were his pets and his toys, and he did as he pleased with them. He built civilisations, constructed religions, and burned empires.

A few bright humans suspected a manipulator. Humans like that were both a danger to him and a special treat. He'd quell their fears by calling himself a benevolent god, or a spirit, or a muse. He'd make them feel special and lavish them with praise and attention until they were putty in his hands. Those were the most fun to play with. Humans with the mental capability to be useful to him were a rare toy that didn't show up often, but ones smart enough to doubt him before things went sour? Practically nonexistent. Ford was once one of his special toys, his favorite one of all. Brainy enough to actually be useful, with a craving for praise, an infinite determination, and a drive to prove himself to be the best.

Then he pushed Bill away.

He understood perfectly well why Ford had chosen to push him out of his life. For all the brain in his head, the little fool didn't seem to truly understand Bill's motives. He wasn't just _destroying_ like some common monster. He was liberating. Without Bill, Ford's stupid, piddly little three dimensional world would forever stay limited, full of laws and should nots and can nots and all of that absolutely foolish _garbage_. He tried to convince Ford to return to him in the only way he knew that worked. Gain trust through flattery but keep loyalty through fear.

Yet somehow, despite everything, despite the _years_ that the two had spent trying to defeat each other, Ford still managed to escape practically unscathed. He managed to roll out of the Nightmare Realm and into dimensions just as easily as Bill had.

Little did he know, he had just given Bill a second chance.

He may have shattered Stanford's trust beyond repair, but he still had a chance with Dipper. All he knew of Bill was the single time when he had invaded Stanley's mind, and that was easy enough to explain away with a few lies about the nature of deals and some nonsense about "seeing what he's got." If Bill could get the stupid little genius on his side before Stan managed to repair the portal and get Ford back, then he'd be able to use him to reshuffle the deck in his favor. Even if Ford managed to return and find out, it'd be hilarious to watch him try to earn Dipper's trust while Stan hates him and his former "muse" whispered his advice in his ear. Lies from a friend are trusted more than truths from a stranger. By the time Dipper figures out the truth (if he ever does) it'll be too late for him to do anything about it.

The party was still on.


	2. Chapter 1:Coffee

He's running as fast as he can. Unfortunately, that isn't very fast. He's in a graveyard, in the forest, by the Mystery Shack, all at once, yet none of these. He's alone, all alone, and the mud sucks at his feet, while the thick air slows his feet and chokes him. He's running underwater, it seems, yet a cold wind still manages to blow through his hair and chill his face. There's a zombie behind him. It groans and howls, stringy, melting, shambling, and thoroughly invincible to anything Dipper can throw at it. Mabel screams somewhere, and somehow through his eyes he can see her struggling to free herself from under a fallen rafter in the Shack as zombies close in on her. He has to get to her.

The zombie behind him is faster than anything he's ever seen, racing towards him despite its femur attempting to dislocate from its pelvis. The creature is green and emaciated, its organs spilling out of a half-collapsed ribcage. It's eyes are pupiless, glowing with an unearthly yellow light that seems to hone in on Dipper like a spotlight. A chunk of its skull is missing and what little remains of its brain is caving in and molding. One leg drags itself across the ground, toes and tarsals alike being left behind in its constant push forward.

He can smell it as it closes in on him, all forest rot and grave dust and the distinct smell of decay that every person knows instinctively. He trips over a tree root that comes lashing out of the ground with the ferocious power of an arm ripping itself out of a grave. The zombie's on top of him, and then its ragged claws are digging into his arms. The background fades to a greenish blur. There is only the zombie.

He's on the ground and can't escape, can't escape. Its mouth lowers into his line of sight and he sees the yellow, jaundiced glowing of its eyes. The zombie rips a chunk of flesh directly from his chest with its teeth, which are falling out, yet terribly sharp. So terribly, horribly sharp. It raises its head and he sees his own blood and the whitish chunks of skin that didn't make it into the monster's throat. He feels the taint of its teeth slowly push out his mind and change what's left of him into a boundless hunger. As he loses himself, he sees Mabel behind the zombie, green.

A sharp, lung filling gasp. Dipper's eyes fly open, but all he sees is the slowly rotting underside of his own roof. Sunlight is coating the rafters, casting slanted shadows against the opposite end of the room. The attic air was already thick and sticky with heat, but Dipper was cold with fright. His head snapped over to look at Mabel's bed of its own accord. Empty. His heart gave a single cold beat before he heard her shouting downstairs. Waddles squealed in response and Mabel laughed.

Dipper turned his head back down and glanced at his watch. His skin had dented redly where it had pressed into him in his sleep, but both his skin and the watch were intact. The red numbers showed it was only a little bit past eight in the morning.

Only one hour of sleep, out of the two hours he'd gotten in the past three days. His fear of having another nightmare kept him awake, as he tried to distract himself with reading and writing down theories. So far he'd only managed to stay awake early morning. Then he'd drop to the pillow and wake up soon afterwards, a new nightmare twisting its way through his imagination.

He flopped backwards and rolled over, shutting his eyes as tightly as he could against the light, but it was too late. The heat and light made it impossible to get back to sleep. With a heavy sigh, he pulled himself back up and rolled out of bed to get dressed.

At first, it had seemed that the zombies hadn't had much of an effect on him. Sure, the original event was terrifying, but it had been solved in a mere night and he had been through worse things before. Gideon had taken over the Shack and kidnapped his sister, Bill had invaded his grunkle's mind, and he put his arm into the Pain Hole. Yet somehow, despite all of these bigger traumas, the zombie nightmares were the most prevalent. He still had the occasional dream about Gideon, but they were mild in comparison to the hordes of undead that used his dreams as a stomping ground (sometimes in the literal sense).

He was so tired.

The bags under Dipper's eyes had grown steadily over the past few days, turning nearly purple with exhaustion. The nightmares had been coming before that, but it was only recently that they'd become bad enough to disturb his sleep. It had gone on long enough that Mabel and even Stan were getting concerned. He brushed it off, citing long periods of studying the paranormal as the reason for his newfound insomniac tendencies. His family didn't seem to notice that he couldn't be studying it, as Stan had taken the journal a few days back. Despite how miffed (and secretly amazed) he was that they hadn't noticed his obvious lie, he had to admit that it had worked out in his favor. If they had brought it up he'd have to come clean about his embarrassing nightmares. That was one thing he certainly didn't want to do.

A massive yawn ballooned inside his throat and he obliged it, stretching his arms upwards and listening to the pops as they traveled up his spine. His nails came back down to rake across an itch on the side of his face as he traveled downstairs to get some breakfast.

Mabel and Waddles were already finished with their breakfasts and had parked themselves on the floor in front of the TV. Mabel was watching yet another poorly-animated 80s children's cartoon about boys and fashion, while Waddles contented himself with simply trying to chew on the yarn Mabel was knitting with, snorting whenever Mabel pulled a strand out of his mouth.

A second yawn pulled itself out of Dipper's mouth as he trudged into the kitchen to get some cereal.

"Hello sugary garbage," he mumbled, "time get into my face".

From there he dropped himself onto a chair, bowl filled, and absently-mindedly began to scoop cereal into his mouth, staring at the wall with half-lidded eyes.

"Forgot your spoon there, kiddo."

Stan was standing in front of the wall Dipper had been staring at, watching him scoop cereal into his mouth with a spoon that wasn't there. Dipper hadn't even noticed Stan's presence until he spoke. The sudden voice snapped his eyes back into focus, forcing him to notice Stan for the first time.

"What?"

"Your spoon. You don't have one."

He looked down. Sure enough, he wasn't even eating his cereal. It had just been sitting in the bowl, slowly going soggy as he rhythmically moved his hand and mouth in a mimic of eating it.

"Oh." Dipper scooted out of his chair and went to retrieve a spoon. He returned to the sound of his great-uncle roughly setting a steaming mug on the table next to his bowl.

"Try this. It helps me with the long nights. Put milk in it if it's too bitter." With that, he simply left, leaving Dipper alone with his newly-acquired spoon and mug.

"Coffee?" Dipper stared at the chipped white mug. It certainly smelled good when Stan had made it every morning, but he had never tried it. His parents assured him that he'd be able to when he was older and it'd be less likely to "stunt his growth", though Dipper was sure that a simple drink couldn't do that.

He pulled the mug closer to him slowly, careful not to spill the contents. The steam warmed his face as he lifted it upwards to his lips. He pulled it back just as rapidly, subconsciously licking at the spot the coffee had burnt. He settled on eating his cereal while waiting for it to cool. A few minutes later, it stopped steaming and he gave it a second shot.

It was even worse this time. It seemed as if something had crawled onto his tongue, vomited, then rotted to death. He immediately set down the mug and scooped more of the sugary cereal into his mouth, hoping to kill the taste before it could cement itself on his tongue.

Gruff laughter came from the doorway. Stan was leaning against it, grinning at him.

"I told you to use milk. Try again."

Dipper begrudgingly removed himself from his chair and got the milk carton out of the refrigerator. The coffee swirled in the mug as a white cloud mushroomed upwards, changing the liquid from a dark black to an inviting shade of golden brown. He took a second swig. It was still bitter, but slightly less so. Eyes squeezed shut, Dipper tipped the mug upwards and chugged it down as quickly as he could. Stan only laughed harder.

"That's one way to do it! Don't worry, you'll get used to 'll have to, if you keep this insomnia thing up." Dipper chose to respond by shoveling more cereal into his mouth to remove the taste. It really was the worst thing he had tasted in his life, and that was even counting the concoctions that Mabel had forced him to taste test over the years.

"Thanks Grunkle Stan."

"No problem, kiddo."

Soon enough Dipper managed to finish his cereal (it really was easier with a spoon in his hand) and placed his dishes in the sink. It was Mabel's turn to do the dishes this week, luckily. Double luckily, the Shack wasn't going to be open for another few days. It seemed that Gideon had all of the gift shop's inventory destroyed to make way for his own. It would take Stan a few more days to reorder new snow globes, bobbleheads, and useless garbage to replace the ones that he had lost.

A short while later, Dipper was upstairs again, sweating into his sheet as he sat on his bed, staring at his ceiling. Stan had promised him that he'd be awake, and he was, but he was also jittery and just as physically tired as before. His heart beat hard inside his chest and it felt like his entire body was trying to vibrate its way through his skin. He wanted badly to sleep, but he couldn't. If he did, he would have another nightmare.

Small black shapes darted around at the edges of his vision. His eyes darted around, attempting to catch them moving, but when he tried to focus on them directly, they'd disappear.

He lay there for an hour, miserably trying to catch the black shapes with his eyes. Sometimes they seemed to be humanoid, but other times they were lower to the ground, or floating in the air formlessly. After a while his heart slowed down and his muscles stopped jittering. Dipper closed his eyes, not caring if it meant he was going to have another nightmare. He was _tired_.

He fell asleep instantly, listening to the sounds of his own slowly relaxing heartbeat in his chest and the whispers that he knew were only in his own mind.

 _He sure gives into sleep more easily than his great-uncle, coffee or no coffee. Good thing, too. It makes my job easier in the long run. Planting nightmares into the mind of a tired, paranoid child is_ much _easier than planting them into the mind of a tired, paranoid adult, especially if the paranoid adult has the willpower to stay awake and away from me._

 _Won't he be surprised when he returns._


	3. Chapter 2:Deal

Another sleep, and with it, another dream. Dipper sprinted for his life yet again, tracing a jagged, curving path through his imaginary forest. Today's zombie infestation was massive, a trailing swarm of shambling, blind monsters charged straight through the forest, completely ignoring the trees that they were phasing through with an ever-increasing speed.

It was that same speed that made Dipper realize that he was running more slowly than before. His legs were sinking into the mud beneath him and the air had turn to liquid. He craned his neck to see behind him, sure that the monsters would be upon him at any moment. Only eyes peered back. The zombies were already nose-deep in the mud, staring back at him and moaning to the best of their ability. As Dipper watched, they sank the down further, slipping into new graves. Dipper's ankles were doing the opposite, the mud and goo slipping off of them and reforming into firm ground. His socks were pristine.

A faint yellow glow in front of him alerted him to something new. His first thought was that another zombie had somehow escaped its muddy fate and was coming up to get him, but when his head snapped forwards he saw nothing at all.

A tap on his shoulder had his head turning back the way it came, then around the other way as the tap came yet again, this time on the opposite shoulder. As he turned around again the yellow became blinding and a small black blur darted forwards to flick his nose. Dipper let out a loud shout.

"Bill!"

"Hey there! Looked to me like you were in trouble, so I dropped in! What's all this mess now? Still shaken up by that whole zombie mess you made?"

"How-how do you know about that? You weren't even there!"

"Of course I was! You just couldn't see me!." Bill lowered himself, materialising his cane and planting it into the mud. He leaned forward. "No one can see me in the Mindscape. Or hear me, feel me, or care about me whatsoever. Gets pretty lonely, to be honest."

"Who cares? You deserve it after what you did to Stan."

"I had to do that. Gideon made a deal with me and it was my only chance to make it out of the Mindscape. I actually showed up here to apologize to you for putting you through all that trouble! I'm sorry."

"But-"

Bill continued, ignoring Dipper's objections. "In fact, I feel so bad about causing you trouble that I'm going to offer you a deal."

"No!"

"Hear me out first, willya? This could really help you out." Bill paused to push a nearby zombie skull further into the sludge."From the looks of it, you need it."

He turned around again, looking Dipper directly in the eyes. "How about this. I'll keep out your nightmares and make sure you get a good night's sleep from now on, and in exchange, all you have to do is let me chat with you in your head! You get the rest that bright little noggin of yours needs, and I finally talk to someone while stuck in the Mindscape! How does that sound?"

"Why would you want to talk to me? Isn't there anyone else in the Mindscape?"

"Not anyone worth talking to! It's mostly just imaginary friends and wraiths out here, and none of them are particularly great conversationalists. Besides, I like you better!"

"Yeah, right."

"Come on, don't let your pathetic self-esteem get in the way. Do you really think you're less fun than a barely-sentient thoughtform? You really scream and everything!" Dipper narrowed his eyes and Bill switched tactics. "Look, if I didn't want to help you, why would I be doing it right now? Without me these zombies would be tearing out your innards. This is probably the first restful sleep you've had in what, three days?"

"How do you know that?"

"Mindscape, remember? I can see the bags under your eyes a dimensional plane away! More proof that you need my help. Now come on kiddo, give my hand a shake. It's a nice, simple, low-stakes deal that'll help us both a lot."

Dipper pulled into himself, crossing his arms and glaring at the ground. "I still don't trust you."

"I realize that I haven't exactly made a good first impression, but that was when I was working under Gideon. I had to follow his orders, and that guy's a creep. If I'm in a deal like this, with a guy like you, things'll be different. I've seen you in action and you don't seem like a creep at all! Sure you're still young, but you're still the bravest, most brilliant person in this little backwoods town."

Dipper's eyebrows arched upwards. "Really?"

"Of course! Admittedly it's low praise, considering the average IQ of the population is about the same as the wildlife, but even in a town full of non-idiots you'd rise above the rest. I feel...like I can trust you, Dipper. You been nothing short of trustworthy in the past. I know it seems risky, but just this once, trust me back."

Bill's hand extended outwards, blue flames curling gently off of the tips of his fingers. It rolled up his wrist and wavered gently there, waiting for an answer.

Slowly, quietly, Dipper began to unfold his arms. His hand reached up, pausing right as the light began to tinge his hand blue. With a slight intake of breath, he closed the distance, placing his hand in Bill's.

"You won't regret this."


End file.
